The present invention relates to a method and apparatus for splicing fibrous mats using heat. More particularly, it relates to a method and apparatus for splicing fibrous mats using a hand-held heating unit to apply heat to the edges of two mats, one or more of which, contain a heat-sensitive adhesive.
The concept of using heat and adhesivess to splice materials is well known. For instance, U.S. Pat. No. 3,449,186 describes a method of splicing plastic coated web material. This process is typically used when packaging articles. A web material is coated with plastic on one side is provided. Two edges of a plastic coated web material are cut forming tearing notches. The plastic coated side of one edge overlaps tearing notches (uncoated) of the other edge and heat is applied to the overlapped edges. With the application of heat, the plastic melts, forming a splice.
U.S. Pat. No. 3,770,555 illustrates an adhesive used for joining materials having a low resistance to heat, i.e., a coated abrasive belt. The free ends of the belt are overlapped and then joined together by a polyurethane, heat-activatable, adhesive film. The preformed adhesive permits joint formation under pressure, at low temperatures, making it possible to join materials which would otherwise cease to join because of their lack of heat resistance.
U.S. Pat. No. 3,661,669 describes a method of joining two strips of material each having a layer of resilient polymeric foam adhered to at least one surface, i.e., carpeting. The edges to be joined are compressed and a tape is bonded to the two strips of compressed foam. A strip of polymeric foam is then inserted into the recessed portion formed by the compressed strips.
U.S. Pat. No. 4,366,014 describes a method for forming joints between the ends of belting, i.e., continuous drive belts. A heating apparatus applies heat and pressure to two adjacent ends of belting causing the two ends to melt. The two melted ends are urged together to form a joint.
U.S. Pat. No. 4,584,040 illustrates a carpet seaming apparatus used to join abutting carpet seams. The seambonding apparatus contains a non-stick, heat reflective material and includes an adhesive tape guide and heating iron attachment point at one end. The apparatus and the iron are pulled along a carpet two abutting carpet seams, as a unit. The melted adhesive adheres to the carpet backing so that the carpet seams are joined.
U.S. Pat. No. 4,767,653 describes a heat-sealable rubbery sheet material made of low-density polyethylene film that is water-tight and resistant to temperature extremes. Further, a method for splicing two sheets together is described. Along the edge of one sheet is a thin layer of heat-sealable adhesive. The sheet containing the adhesive is placed on top of an adjacent sheet of material so that the edge of the adhesive sheet overlaps the adjacent sheet. Heat is then applied to the so that bonding to the sheets occurs.
U.S. Pat. No. 5,104,475 discloses a method for seaming for carpets that are installed by gluing pieces of carpet directly to a substrate. After the carpet pieces have been glued down, a carpet seaming tape is applied along the abutting seams of carpet. Adhesive is then applied to the seams and an electric seaming iron is moved along the length of the carpet seaming tape to melt the adhesive. The abutting carpet pieces are then pressed into the adhesive.
U.S. Pat. No. 5,329,094 illustrates a method and apparatus for performing splices in resilient plastic waterstops (used to provide a seal between slabs of concrete). The splicing apparatus includes a pair of radiant heating elements which are mounted horizontally to one another. A splice is made by positioning the juxtaposed ends of adjoining waterstop sections in the heated regions along the sides of the heating apparatus until the ends of the waterstop have softened. After softening the ends, they are joined together and cooled to form a welded seam.
U.S. Pat. No. 5,584,897 describes a method for making a coated abrasive belt by splicing two free ends of a polymeric or cloth backing sheet and then applying fibrous reinforcing material, a binder precursor and then an abrasive coating comprising binder and abrasive particles. The splice used is either a xe2x80x9clap splicexe2x80x9d or a xe2x80x9cbutt splicexe2x80x9d. In a xe2x80x9clap splicexe2x80x9d, two free ends of the backing sheet are beveled in a tapered manner so that the top end and bottom end of the sheet can be fit together to form a joint without causing a change in the thickness of the belt. In a xe2x80x9cbutt splicexe2x80x9d, two free ends of the backing sheet are brought into juxtaposed relationship with the faces of the ends in confronting abutment so that they can be joined by adhesives, tape, or staples.
U.S. Pat. No. 5,486,249 illustrates a thermoplastic film for heat seaming roof sheeting. A thermoplastic film is interposed between the overlapped edges of two layers of roof sheeting material to form a seam. The overlapped area is heating to a temperature sufficient to melt the film, bonding the two layers of sheeting at the seam.
More recently, U.S. Pat. No. 5,618,377 discloses an apparatus and method for continuously splicing a thermally-shrinkable film, i.e., polyethylene film used for packaging. An edge portion of a first film, fed from a first roll, and an edge portion of a second film, fed from a second roll, are clamped by clamps on the splicing apparatus. At the desired splicing location a heater, advances and heat-seals the ends of the films so that they are connected.
All of the above patents teach methods and apparatus for splicing materials such as polyethylene films, rubbers, and various other plastics by overlapping one edge of the material over the other. None of the prior art specifically addresses splicing fibrous mats. In the past, fibrous mats were spliced by sewing the ends of two fibrous mats together.
Currently, splicing of the trailing edge of one fibrous mat to the leading edge of another fibrous mat is to sew the two mats together. This is done by splitting the trailing edge into two equal strips about 6 inches long. The leading edge of the new mat is then sandwiched between the two halves of the trailing mat and a sewing thread (glass or polyester) is used hold them together using a straight stitch. In some cases, to reduce the overall thickness of the splice, part of either or both mats is cut off. For example, the leading edge of the new mat is split into two equal parts and then cut off of one of the two split sections before inserting this mat into the split created in the trailing mat.
The sewing of two fibrous mats together has a major disadvantage in that the splice can be easily identified in the finished part, especially the sewing thread. Pultruded parts requiring a smooth unblemished surface must be scraped to remove the spliced section, causing a great deal of waste.
Fibrous mats are normally used as reinforcement in manufacturing composite materials in general. The major application for this splicing solution is the pultrusion process where a continuous cross-sectional profile is desired. The advantage to splicing with a polyamide tape is that it does not show in the surface of the finished part and does not affect the finished part strength. The most common resin for pultrusion is a thermoset. As heat in the die starts to weaken the splice made with polyamide tape the thermoset resin has begun to harden locking the splice in the finished part.
Thus, there is a need for a method to splice fibrous mats to create a strong joint between two mats and also to provide an aesthetically appealing product.
The present invention relates to a method and apparatus for splicing fibrous mats. More particularly the invention relates to separating an edge of one fibrous mat into two sections, inserting an adhesive-containing edge of another fibrous mat between the two sections and applying heat to the adhesive-containing edge. Upon cooling, both of the mats are bonded together and the splice is complete.
Heating the mats can be carried by any conventional heating unit, however, the preferred heating unit is a hand-held device containing two adjacent heating elements affixed to a handle. The heating elements xe2x80x9cclampxe2x80x9d the area where the mats are to be joined and evenly distribute heat so that the adhesive melts and the edges of the mats are securely bonded together.
It is an object of the present invention to provide a method of splicing fibrous mats which results in a strong bond between two fibrous mats after the splice is made.
It is an object of the present invention to provide a method of splicing fibrous mats resulting in a visually appealing final product.
It is another object of the present invention to provide a hand-held heating apparatus that can splice splicing fibrous in a timely manner.
The foregoing and other advantages of the invention will become apparent from the following disclosure in which one or more preferred embodiments of the invention are described in detail and illustrated in the accompanying drawings. It is contemplated that variations in procedures, structural features and arrangement of parts may appear to a person skilled in the art without departing from the scope of or sacrificing any of the advantages of the invention.